Answer all the questions, i.e. Address and port of OCS Inventory Server
For the rest, use default answers (mostly yes).
Compiling should not take that long.
Wait until it is finished, if you see error messages, you can view ocs_agent_setup_log for details.

Performing an Inventory

Simply launch ocsinventory-client.pl
Wait a few seconds, then login onto your OCS Inventory Server to verify that it worked.